Download CWShredder
Make sure ALL browsers and any open windows are closed before running CWShredder. Click the *Fix button (not the scan only) and follow the instructions you will receive when the program runs.

Then make sure you have the most recent versions of AdAware and Spybot Search & Destroy, and that you have brought them up todate before scanning with them.

Check that you have All the Critical Updates for both your operating system and Internet Explorer installed: Microsoft's Update Site.

Then once you have downloaded Hijackthis, create a new, permanent folder on your C drive and unzip Hijackthis.exe into the new folder. Run the program, then when the scan is finished, the "Scan" button will then change to a "Save Log" button. Press the "Save Log" button. Copy and paste the entire contents of the log here in this thread. Someone will review your log and give you instructions on what needs to be fixed.

NOTE: Most of what it lists will be harmless and even essential - so, do NOT fix anything yet.